Ladybugs are the subject of nursery rhymes and are considered a good luck symbol by many. These beetles usually considered to be beneficial insects because they feed on plant pests and they live outdoors. Although most ladybugs are harmless and good for the environment, the recently introduced Asian Lady Beetle (harmonia axyridis) is an exception. Unlike its docile relative, this orange ladybug can be aggressive and bite.
Spotting the Difference Between Good and Bad Ladybugs
At a quick glance, it can be hard to tell the difference between the Asian ladybug and beneficial ladybugs, partly because the color of the Asian species can vary from light tan or orange to bright red. But if you look closely, you will see the Asian lady beetle has a white marking behind its head in the openings of what looks like a black M. Some also have dark black spots, but on others, the spots are very light or nonexistent.
How the Asian Lady Beetle Was Introduced to the United States
This ladybug species was purposely introduced into the U.S. from Asia in the latter half of the 1900s by the U.S. Department of Agriculture (USDA) to control agricultural pests, such as aphids and scale insects. The USDA released the lady beetles in Georgia, South Carolina, Louisiana, Mississippi, California, Washington, Pennsylvania, Connecticut and Maryland, and since then it has migrated so that it is now found throughout most of the United States. In addition to this intentional introduction, the beetles have been accidentally introduced to the U.S. on freighters, which probably caused or increased its presence across the country.
Asian Lady Beetle Infestations
Since their purposeful introduction, however, the not-so-beneficial aspects of this species of ladybug have come to light. Like boxelder bugs and stink bugs, Asian Lady Beetles will crawl into cracks and crevices of the home like the eaves, siding, or even the foundation to overwinter between the walls. They can then come into the house through the winter seeking its warmth.
Once inside, they will crawl or fly around rooms, and land on windows, walls, and furniture. Having these bugs flying around your home can be bad enough, but worse is the terrible odor and yellowish fluid they can secrete if disturbed. This fluid can stain walls, furniture, and other surfaces on which they crawl.
Some people can have allergic reactions to the beetles, especially if there are a lot of them. Allergenic reactions can vary from eye problems, such as conjunctivitis (or "pink eye"), to hay fever, cough, asthma, or hives. Reactions can be triggered by touching the lady beetles then touching your eyes, or just by being around a large or lengthy infestation.
Asian Lady Beetles can be aggressive and bite if they land on the skin. Although the Asian lady beetles do help rid gardens of plant pests, they are becoming a problem in vineyards, where they can end up being "collected" along with the grapes resulting in an "off" taste in the wine.
Controlling Asian Lady Beetles
The best way to control Asian lady beetles in your home is through pest-proofing measures to keep them from entering. These include sealing any cracks around windows, doors, utility wires and pipes, and vents, as well as in siding, eaves, and the foundation. It also is important to be sure that all doors and windows are tightly fitted, and screens are not torn or ripped. If the ladybugs do get in your home, they can be vacuumed or captured on sticky tape. To avoid staining and odor, do not try to swat or squash the bugs.